Which of the following best describes the electron transport chain?

• A. A pathway that breaks down fatty acids into acetyl-CoA
• B. A cycle that fixes carbon dioxide into organic molecules
• C. A series of protein complexes that transfer electrons to generate ATP
• D. A process that directly converts glucose into pyruvate

Answer: (C)

Verified step by step guidance

1. Begin by understanding the role of the electron transport chain (ETC) in cellular respiration. It is the final stage of aerobic respiration, occurring in the inner mitochondrial membrane.
2. Recognize that the ETC consists of a series of protein complexes and other molecules that facilitate the transfer of electrons from electron donors to electron acceptors via redox reactions.
3. Understand that as electrons move through the ETC, they release energy. This energy is used to pump protons across the mitochondrial membrane, creating a proton gradient.
4. Learn that the proton gradient generated by the ETC is used by ATP synthase to synthesize ATP from ADP and inorganic phosphate, a process known as chemiosmosis.
5. Identify that the ETC does not directly convert glucose into pyruvate, nor does it break down fatty acids into acetyl-CoA or fix carbon dioxide into organic molecules. Its primary function is to generate ATP through electron transfer.